Abstract:

X-band active phased array radars are widely used in missile defense,weather monitoring and other fields.The phase shifter is the critical function circuit in the transceivers with an active phased array,and exists widely in the whole active phased array.In view of the problem that high-integration and high-precision cannot be simultaneously met under the broadband of a large phase-shifting unit,a compacted 6-bit digital phase shifter applied in the X-band is designed based on the 0.18 μm SiGe BiCMOS process.By means of cascade 6 different phase shifting units,the phase shifter can achieve a minimum phase shifting step of 5.625° in the range of 360° phase shifting.In addition,in order to reduce the area of the chip,this design proposes an embedded switching structure for the 90°phase shifting unit,which greatly reduces the area of the chip compared with the traditional structure where the large unit chooses the path by switching.The deep-well NMOS transistor is used as the switch to control the working state of each phase shift unit with the floating body technology which is used to improve the switch isolation by reducing the parasitic capacitance of the transistor to the ground.Simulation results show that within the 8.3~12.0 GHz,the RMS phase error is less than 2.5°,that the insertion loss is less than -16.73 dB,and that the RMS amplitude error is less than 1.25 dB.The chip core layout area is 1.68 mm×0.64 mm.

Key words: phase shifters, bandpass filters, transceivers